The Dragon Square Shield can be obtained either from; Players, the Grand Exchange, or smithed.

The Dragon Square Shield is in two separate parts, Left and Right. The Right half can be bought from the Grand Exchange, Players or from the Legends' Guild for a high price of 750,000gp. The Left half can also be bought from the Grand Exchange, Players, and can be received as a rare drop from assorted Monsters.

It is recommended that rather than smithing the shield and buying the parts separately, that you buy the complete shield from the Grand Exchange as it is alot cheaper.